How effective is it? Over 99% effective – less than 1 woman per 100 will get pregnant over five years.

How does it work? The small T-shaped plastic device releases progesterone (reproductive hormone) which stops sperm from reaching the egg, stops a fertilised egg implanting and may stop eggs from being released (ovulation).

How long does it last? The IUS can be left in for 5 years but can be removed sooner if necessary.

How does it affect periods? They usually become lighter, shorter and less painful. They may stop all together.

How does it affect fertility? When the IUS is removed fertility will return to normal.

How is it put in and taken out? A doctor/nurse will insert the IUS; it takes 15-20 minutes. It can be painful and a local anaesthetic may be used. The IUS has 2 soft threads, which hang down through the cervix into the top of the vagina. The IUS can be removed by a doctor/nurse pulling on these threads.